Evolution of the antimicrobial resistance of Pseudomonas aeruginosa in Spain: second national study (2003)

The second national prevalence study of Pseudomonas aeruginosa has been carried out in Spain. A total of 1250 clinical isolates of P. aeruginosa were collected from 127 hospitals in 1 week in 2003 and the resistance data gathered from the isolates was compared with those of the first study in 1998 (1014 isolates from 136 hospitals). Antimicrobial susceptibility testing was performed in both studies in the same laboratory. The most active antimicrobials were piperacillin, piperacillin-tazobactam, and amikacin (< or =10% resistant) and resistance to these antimicrobials did not change over the time. The least active were ofloxacin and gentamicin (> or =30% resistant). From 1998 to 2003, resistance increased significantly to ciprofloxacin (23% vs. 28%, respectively, p=0.015); ofloxacin (30% vs. 37%, p=0.002); imipenem (14% vs. 18%, p=0.017) and meropenem (8% vs. 13%, p <0.001). Resistance to aztreonam (23%), ceftazidime (16%), cefepime (20%), ticarcillin (13%) and tobramycin (11%) remained stable. Isolates from inpatients were significantly more resistant than those from outpatients to all antimicrobials, with the exception of fluoroquinolones and aminoglycosides (p <0.01). Isolates from outpatients were significantly more resistant to these two groups (p <0.05) than to other antimicrobials. In Spain, from 1998 to 2003, the susceptibility pattern of P. aeruginosa to antimicrobial agents has changed. Isolates have become significantly more resistant to fluoroquinolones and carbapenems. However, resistance to beta-lactams and aminoglycosides remains stable.